<?php

/**
 * An interface for OpenID extensions.
 *
 * @package OpenID
 */

// Do not allow direct access
defined( '_JEXEC' ) or die( 'Restricted access' );

/**
 * Require the Message implementation.
 */
require_once 'Auth/OpenID/Message.php';

/**
 * A base class for accessing extension request and response data for
 * the OpenID 2 protocol.
 *
 * @package OpenID
 */
class Auth_OpenID_Extension {
	/**
	 * ns_uri: The namespace to which to add the arguments for this
	 * extension
	 */
	var $ns_uri = null;
	var $ns_alias = null;

	/**
	 * Get the string arguments that should be added to an OpenID
	 * message for this extension.
	 */
	function getExtensionArgs()
	{
		return null;
	}

	/**
	 * Add the arguments from this extension to the provided message.
	 *
	 * Returns the message with the extension arguments added.
	 */
	function toMessage(&$message)
	{
		$implicit = $message->isOpenID1();
		$added = $message->namespaces->addAlias($this->ns_uri,
												$this->ns_alias,
												$implicit);

		if ($added === null) {
			if ($message->namespaces->getAlias($this->ns_uri) !=
				$this->ns_alias) {
				return null;
			}
		}

		$message->updateArgs($this->ns_uri,
							 $this->getExtensionArgs());
		return $message;
	}
}

?>